Radiocondenser



Dec. 2, 1924.- 1,517,370

R. E. MARBURY FAD LOCONDENSER Filed Nov. 26. 1920 4 5 waan? Mina nINVENTOR E SES: 51% BYRa/ph E'. Marbury.

.mW/0W l AT'ToRNEY WITN Patented Dec. y2, 1924.

UNITED srarlas,PAT-lam orifice.

RALPH n rumaenien HOUSE ELECTBIICVAND MANUFACTURING COMPANY, ACORPORATION OF PENNSYL- vente.v

` i RADIOGONDENSEB.

Application ledrllovember, 1920., Serial No. 428,432.

with thin sheetsv of metal foil, such as cop-,r are then pressed er.-`The. assembled layers Eetweenclamps to reduce the air spaces between thevarious layers. Such condensers have rather high losses due to airpockets between the metal foil and mica sheets on account of they lackof intimate contact between the mica and the metal. This isattributableto the irregularities in the mica which are inherent inthe plate-likestructure thereof. i d.

It has been" attempted to .overcome this diiculty by forming condenserbodies with v alternate layers of mica andcopper having sheets of leadfoil between the mica an copper layers. The Aassembly `was compressed ata very high pressure to cause the lead foil to flow and fill up theirregularities in the mica, displacing any air present. Since thesurface of the mica lsheet is irregular,

such tremendous pressures used often causedl high spots in the mica tobe broken down or crushed. The pressures used 4also caused cracks to.develop in the mica, ,reducing the efficiency and the life of thecondenser.'

The present inventionlobviates such disadvantages, it being amen theobjects thereof to provide a method o constructing oo ndensers embodyinga solid dielectric, which shall have low Apower losses and be veryeiiicient when used with high frequencyfc'urrents.

My invention contemplates a method of forming condensere in which theirregular surfaces of the mica remain practically undamaged, and inwhich the irregularities are entire y filled in, and no air pockets arealinvenwhich lowed to remain. In practising m tion, I provide sheetseofmetal foi,

invention relates to condensers, more l for use 1n part hereof and whicillustrate a specific are coated with a thin film ofian easily fusiblemetal and then stacked with alternate y layers `of `mica to form yacondenser body.

The condenser body is placed under pressure, heat bein applied to softenor melt the easily fusi le metal, and a moderate ressure applied toconsolidate the various ayers ofmaterial and cause the fusible metal toflow into the irregularities in the surface of the mica.

In the accompanyin drawings forming a embodiment of m invention,

F1g.r1ris an en arged sectional viewof a sheet of mica and a, sheet ofcoated metal foil, and f Fig. 2 is asimilar view showing the intimateunion of mica and `metal after the condenser is completed.

Mica sheets 1, such as are ordinaril em- ;ployed in condensers, haveirregular s aped Lpro'ections 2 and depressions 3, exaggerated as s ownin the drawings. Suchdepressions vare ordinarily not filled incondensers constructed inaccordance With'prior methods and constituteair-pockets whichy eatl interferey wlth the proper functioning o thecondenser. My invention utilizes a thin foil 4 ofv any suitable metal,such as copper,

n which is coated on both sides with a thin film of easily fusible metal5 such as Woods metal having a melting point of about 75 C.

The film maybe of any desired thickness and may be provided in anysuitable way. Prefera l I form such film bypassing the copper stripsthrough a weak acid solution and then throughr a molten bath of Woodsvmetal so as to provide a thin film about 1/1000 of one inch thick oneach side thereof. The copper strips may then be punched or cut intoplates ofA proper size and then stacked alternately with sheets of micain any desired manner. The assembled layers are then placed under amoderate pressure of a few hundred pounds and heat a plied to raise thetemperature of the condenser body to about 75 ing to melt and conform tothe irregularities 2 and 3 in thesurface of the mica, asshown in Fig. 2.

I generally prefer to ap ly pressure and heat simultaneously but 1t isimmaterial whether the pressure is applied simultaneously with, before,or after the heating. If

C., causing the metal coatnnenwoon PARK, PENNSYLVANIA, AssrGNon 'roWEs'rING- desired, the heating` and pressure may be accomplished morereadily by placing the condenser 'in a vacuum. If desired, a coatin ofwax may be applied to the `condenser beore removing from vacuum. Thecondenser is thenclamped while under pressure and allowed to cool.

I generally naine Woods man, which consists of onepart cadmium, fourparts bismuth, two parts lead and one part tin.

Although I prefer touse this metal, which f 1. A metho Voflformingcondensers which f comprises coating sheets of metal foilr with a metalfusibleV below 200 C, and assembling nate sheets of solid dielectric.

2. A method of forming condensers which comprisescoating sheets of metalfoil with a metal fusible below 200 C, and assembling a suitable numberof such foils with alternate sheets of mica.

3. A method of forming condensers which comprises coating sheets ofmetal foil with an easily fusible metal, and 'assembling a suitablenumber of such foils with alternate sheets of solid dielectric andapplying heat thereto to fuse said fusible metal.

4. A method of forming condensers which comprises coating sheets ofmetal foil with an easily fusible metal, assembling a suitable number ofsuch ,foils with alternate sheets of solid dielectric, applying' heatthereto, and placing the assembly under pressure to cause said fusiblemetal to fiow into the irregularities in said dielectric.

5. A method of forming condensers which kcomprises'coating sheets of,metal foil with an easily fusible metal, assembling a suit- Similaralloys, embodying the same sheets of metal foil and mica havin ymoderatepressure to cause said fusible metal to flow into the irregularities insaid dielectric.

` 6. A method of `forming conden-sers which comprises coatingsheets ofmetal foil vwith an easily fusible metal, assembling Va suitable numberof such foils with alternate sheets of solid dielectric, applying heatthereto, placing the assembly under moderate pressure to cause saidfusible metal to fiow into the irregularities in said dielectric, andcovering said condenser with wax.

7. A method'of forming condenserswhich comprises coating. sheets ofmetalfoil with lVoods e meta-l, and assembling a suitable number of suchfoils with alternate sheets of solid dielectric. V

8. A method of forming eondensers which comprises coating sheets ofmetal foil with Woods meta-l, assembling a suitable numn ber ofsuchfoils with alternate sheets of solid dielectric, andheating toaboutl 75.

9'. A method of forming condensers which comprises coating sheets ofmetal `foil with Woods metal, assembling a suitable numa suitablenumberof such foils with alter"' ber ofsuch foils with alternal sheetsof mica, heating tofabout 75 C.,"' nd placing said assembly undermoderate ressure to cause said fusible'metal to flow into theirregularities yin saidmica.

10. 'A condenser comprising `alternate sheets of metal foil and soliddielectric having metal fusible below 200 C. between said sheets. j y

11. A condenser comprising alternate sheets of metal foil and a sollddielectric haing irregularities in the surface thereof, an sheets andpro'ecting into said irregularities.

12. A rcon enser comprising alternate metal fusible below 200 C. betweensaid s eets.

13. A condenser comprising alternate sheets of metal foil and micahaving lVoods metal between said sheets.4

lIn testimony whereof, I have hereunto subscribed my name this 12th dayof November,

RALPH E. MARBURY.

metalfusible below 200` C. between said'

